Re mobile phones : Apparantly there is a facility whereby the networks can be closed down (closing any existing connections) and then re-opened to specified user groups only. Emergency workers, govt officials etc have priority user groups - and will be able to make and recieve calls (ordinary bods are something like group 6). This is probably what you mean.
As to UK : As far as I can make out all airports have been closed until further notice, Canary Wharf, the City square mile and Houses of Parliament &tc are being evacuated. All planes which left Britain & were able to turn back have been turned back & will return to Britain.
Apparantly there are still two planes lost & out of contact from United Airlines - but obviously everything is very confused & that may be a reference to planes already down.
Feeling terrible for everyone - especially our NY catters.
Kris